Social isolation among the elderly is consistently linked to a wide variety of deleterious consequences that range from an increased risk of institutionalization to decreased life-expectancy. Although correlational evidence suggesting a relationship between social behavior and health is provocative, very little is known about specific behavioral or physiological factors that are involved. Thus, social isolation may be confounded with other variables which are themselves predictive of impairments in health and social functioning. Losses in memory, the ability to discriminate and recognize faces, and to retrieve words necessary for conversational speech, for example, could produce a decrease in the frequency of interactional behavior. Given brain changes related to normal aging, as well as dramatic increases in the incidence of organic brain syndromes among an aged population, the potential role of cognitive deficits in social isolation is sorely in need of investigation. In this work, the neuropsychological status of socially isolated and socially active elderly nursing home residents will be assessed using tests that measure intellectual functioning, memory, visuospatial functions and language, as well as perceived social isolation. It is postulated that relative to socially active elderly, a significant number of socially isolated persons are deficient in cognitive skills necessary for effective social interactions. The long-term objective of this research is to more fully understand the relationship between social contact and physical health status. Findings will be important for two reasons: First, if a significant percentage of isolated elderly also experience cognitive deficits, the underlying basis of these deficits will need to be closely examined; particularly the potential confounding of organic brain syndromes and social isolation. Second, to date, the focus of interventions has been almost exclusively on increasing rates of interpersonal interaction without regard to the potential diversity of the target population. If a large number of isolated elderly display significant deficits in neuropsychological functioning, this must become an important consideration in planning effective interventions.